Data Management Plan

A team from the Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) deployed on a two-week research cruise in November 2015 to evaluate the impacts of the 2015 mass coral bleaching event in the Main Hawaiian Islands via towed-diver surveys. Areas surveyed included south Oahu, west Maui, Lana’i, and west Hawaii island. Over the course of 10 survey days, the team surveyed approximately 90 km of 15-m wide transects at depths ranging from 2 to 10 m.

Data provided in this dataset include visual estimates recorded by towed divers of percentage of live coral that was pale and bleached, as well as presence/absence data of condition by generic composition. Analysis of observer data reveals estimates of live coral affected by the event (pale or bleached) show a regional mean of 38.8% (+/- 1.96% CI95), with large variation in impact apparent between transects on the same island separated by as little as 13 km.

Additionally, instruments mounted on the towboards collected other in-situ data that are documented separately. A downward-facing DSLR camera with strobes collected photographic quadrat data by capturing an image of the benthos at 15-second intervals during the surveys. Oceanographic data was collected continuously throughout each survey with a suite of mounted sensors recording conductivity, temperature, depth, flourometry (chlorophyll-a), turbidity and dissolved oxygen.

The towed-diver visual estimate data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

Extent of underwater surveys in Main Hawaiian Islands in November 2015.

Process Steps:

• A pair of scuba divers is towed about 1 m above the reef roughly 30 m behind a small boat at a constant speed of about 1.5 kt. Both divers collect visual observations of the benthos. Towboards are connected to the small boat by a bridle and towline. A tow survey is typically 50 minutes and covers about 2 km of habitat. Each survey is divided into 5-minute segments, with data recorded per segment to allow observations to be georeferenced within the ~200 m covered during each 5-min segment. Throughout a survey, the latitude and longitude of the survey track is recorded at 5-second intervals on the small boat with a global positioning system (GPS). Following a survey, towed-diver tracks are generated using this GPS data and a layback algorithm to account for the position of the diver relative to the small boat. For each 5-minute tow segment, each diver notes live coral cover, the percentage of that cover that is noticeably pale, and the percentage of that cover that is bleached. They also record the presence/absence of condition classes of each of the five major coral genera/morphologies found in Hawaiian waters, specifically, Pocillopora, Montipora, Porites massive, Porites branching, Pavona, and other. Each genus is also noted as the presence/absence of the conditions: healthy, pale, bleached, and recently dead.

Observations, including species identification and coverage area estimates were periodically checked during the expedition for consistency between divers. Data entry was usually conducted on the same day as the surveys using MS Access. Data was quality controlled by the divers using a two-person system. The data was then run through rigorous quality control checks by the data management team before the data was migrated to the Oracle database. Given the size of the data set, there remains some possibility of typographical or other errors.

Data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

NOAA IRC and NOAA Fisheries ITS resources and assets.